diff --git a/internal/runtime/executor/github_copilot_executor.go b/internal/runtime/executor/github_copilot_executor.go
index d1391480..2c640f93 100644
--- a/internal/runtime/executor/github_copilot_executor.go
+++ b/internal/runtime/executor/github_copilot_executor.go
@@ -385,7 +385,19 @@ func (e *GitHubCopilotExecutor) ExecuteStream(ctx context.Context, auth *cliprox
 			if useResponses && from.String() == "claude" {
 				chunks = translateGitHubCopilotResponsesStreamToClaude(bytes.Clone(line), &param)
 			} else {
-				normalizedLine := normalizeGitHubCopilotReasoningField(bytes.Clone(line))
+				// Strip SSE "data: " prefix before reasoning field normalization,
+				// since normalizeGitHubCopilotReasoningField expects pure JSON.
+				// Re-wrap with the prefix afterward for the translator.
+				normalizedLine := bytes.Clone(line)
+				if bytes.HasPrefix(line, dataTag) {
+					sseData := bytes.TrimSpace(line[len(dataTag):])
+					if !bytes.Equal(sseData, []byte("[DONE]")) && gjson.ValidBytes(sseData) {
+						normalized := normalizeGitHubCopilotReasoningField(bytes.Clone(sseData))
+						if !bytes.Equal(normalized, sseData) {
+							normalizedLine = append(append([]byte(nil), dataTag...), normalized...)
+						}
+					}
+				}
 				chunks = sdktranslator.TranslateStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), body, normalizedLine, &param)
 			}
 			for i := range chunks {
@@ -601,14 +613,6 @@ func isAgentInitiated(body []byte) bool {
 					}
 				}
 			}
-			// Fallback: if ANY message has role "tool", this conversation
-			// involves tool use — mark as agent to cover compaction and
-			// multi-turn agent continuations.
-			for _, msg := range arr {
-				if msg.Get("role").String() == "tool" {
-					return true
-				}
-			}
 		}
 
 		return false
@@ -740,19 +744,28 @@ func isCopilotUnsupportedBeta(beta string) bool {
 // (choices[].delta.reasoning_text) and non-streaming messages
 // (choices[].message.reasoning_text). The field is only renamed when
 // 'reasoning_content' is absent or null, preserving standard responses.
+// All choices are processed to support n>1 requests.
 func normalizeGitHubCopilotReasoningField(data []byte) []byte {
-	// Non-streaming: choices[].message.reasoning_text
-	if rt := gjson.GetBytes(data, "choices.0.message.reasoning_text"); rt.Exists() && rt.String() != "" {
-		rc := gjson.GetBytes(data, "choices.0.message.reasoning_content")
-		if !rc.Exists() || rc.Type == gjson.Null || rc.String() == "" {
-			data, _ = sjson.SetBytes(data, "choices.0.message.reasoning_content", rt.String())
-		}
+	choices := gjson.GetBytes(data, "choices")
+	if !choices.Exists() || !choices.IsArray() {
+		return data
 	}
-	// Streaming: choices[].delta.reasoning_text
-	if rt := gjson.GetBytes(data, "choices.0.delta.reasoning_text"); rt.Exists() && rt.String() != "" {
-		rc := gjson.GetBytes(data, "choices.0.delta.reasoning_content")
-		if !rc.Exists() || rc.Type == gjson.Null || rc.String() == "" {
-			data, _ = sjson.SetBytes(data, "choices.0.delta.reasoning_content", rt.String())
+	for i := range choices.Array() {
+		// Non-streaming: choices[i].message.reasoning_text
+		msgRT := fmt.Sprintf("choices.%d.message.reasoning_text", i)
+		msgRC := fmt.Sprintf("choices.%d.message.reasoning_content", i)
+		if rt := gjson.GetBytes(data, msgRT); rt.Exists() && rt.String() != "" {
+			if rc := gjson.GetBytes(data, msgRC); !rc.Exists() || rc.Type == gjson.Null || rc.String() == "" {
+				data, _ = sjson.SetBytes(data, msgRC, rt.String())
+			}
+		}
+		// Streaming: choices[i].delta.reasoning_text
+		deltaRT := fmt.Sprintf("choices.%d.delta.reasoning_text", i)
+		deltaRC := fmt.Sprintf("choices.%d.delta.reasoning_content", i)
+		if rt := gjson.GetBytes(data, deltaRT); rt.Exists() && rt.String() != "" {
+			if rc := gjson.GetBytes(data, deltaRC); !rc.Exists() || rc.Type == gjson.Null || rc.String() == "" {
+				data, _ = sjson.SetBytes(data, deltaRC, rt.String())
+			}
 		}
 	}
 	return data
diff --git a/internal/runtime/executor/github_copilot_executor_test.go b/internal/runtime/executor/github_copilot_executor_test.go
index 909e4d32..90a5b26f 100644
--- a/internal/runtime/executor/github_copilot_executor_test.go
+++ b/internal/runtime/executor/github_copilot_executor_test.go
@@ -324,13 +324,13 @@ func TestApplyHeaders_XInitiator_AgentWhenLastUserButHistoryHasAssistant(t *test
 	t.Parallel()
 	e := &GitHubCopilotExecutor{}
 	req, _ := http.NewRequest(http.MethodPost, "https://example.com", nil)
-	// When the last role is "user" but the conversation contains tool messages,
-	// the request is a continuation (e.g. tool result with attached text
-	// translated to a synthetic user message). Should be "agent".
-	body := []byte(`{"messages":[{"role":"user","content":"hello"},{"role":"assistant","content":"I will read the file"},{"role":"tool","content":"file contents..."},{"role":"user","content":"tool result here"}]}`)
+	// When the last role is "user" and the message contains tool_result content,
+	// the request is a continuation (e.g. Claude tool result translated to a
+	// synthetic user message). Should be "agent".
+	body := []byte(`{"messages":[{"role":"user","content":"hello"},{"role":"assistant","content":"I will read the file"},{"role":"user","content":[{"type":"tool_result","tool_use_id":"tu1","content":"file contents..."}]}]}`)
 	e.applyHeaders(req, "token", body)
 	if got := req.Header.Get("X-Initiator"); got != "agent" {
-		t.Fatalf("X-Initiator = %q, want agent (history has tool role)", got)
+		t.Fatalf("X-Initiator = %q, want agent (last user contains tool_result)", got)
 	}
 }
 
@@ -338,10 +338,11 @@ func TestApplyHeaders_XInitiator_AgentWithToolRole(t *testing.T) {
 	t.Parallel()
 	e := &GitHubCopilotExecutor{}
 	req, _ := http.NewRequest(http.MethodPost, "https://example.com", nil)
+	// When the last message has role "tool", it's clearly agent-initiated.
 	body := []byte(`{"messages":[{"role":"user","content":"hello"},{"role":"tool","content":"result"}]}`)
 	e.applyHeaders(req, "token", body)
 	if got := req.Header.Get("X-Initiator"); got != "agent" {
-		t.Fatalf("X-Initiator = %q, want agent (tool role exists)", got)
+		t.Fatalf("X-Initiator = %q, want agent (last role is tool)", got)
 	}
 }
 
@@ -392,17 +393,17 @@ func TestApplyHeaders_XInitiator_UserInMultiTurnNoTools(t *testing.T) {
 	}
 }
 
-func TestApplyHeaders_XInitiator_AgentCompactionWithToolHistory(t *testing.T) {
+func TestApplyHeaders_XInitiator_UserFollowUpAfterToolHistory(t *testing.T) {
 	t.Parallel()
 	e := &GitHubCopilotExecutor{}
 	req, _ := http.NewRequest(http.MethodPost, "https://example.com", nil)
-	// Compaction scenario: user prompt after a conversation with tool use history.
-	// The last message is a plain "user" message (compaction summary request),
-	// but the conversation contains tool messages → should be "agent".
+	// User follow-up after a completed tool-use conversation.
+	// The last message is a genuine user question — should be "user", not "agent".
+	// This aligns with opencode's behavior: only active tool loops are agent-initiated.
 	body := []byte(`{"messages":[{"role":"user","content":"hello"},{"role":"assistant","content":[{"type":"tool_use","id":"tu1","name":"Read","input":{}}]},{"role":"tool","tool_call_id":"tu1","content":"file data"},{"role":"assistant","content":"I read the file."},{"role":"user","content":"What did we do so far?"}]}`)
 	e.applyHeaders(req, "token", body)
-	if got := req.Header.Get("X-Initiator"); got != "agent" {
-		t.Fatalf("X-Initiator = %q, want agent (compaction with tool history)", got)
+	if got := req.Header.Get("X-Initiator"); got != "user" {
+		t.Fatalf("X-Initiator = %q, want user (genuine follow-up after tool history)", got)
 	}
 }
 
@@ -502,6 +503,61 @@ func TestApplyGitHubCopilotResponsesDefaults_NoReasoningEffort(t *testing.T) {
 	}
 }
 
+// --- Tests for normalizeGitHubCopilotReasoningField ---
+
+func TestNormalizeReasoningField_NonStreaming(t *testing.T) {
+	t.Parallel()
+	data := []byte(`{"choices":[{"message":{"content":"hello","reasoning_text":"I think..."}}]}`)
+	got := normalizeGitHubCopilotReasoningField(data)
+	rc := gjson.GetBytes(got, "choices.0.message.reasoning_content").String()
+	if rc != "I think..." {
+		t.Fatalf("reasoning_content = %q, want %q", rc, "I think...")
+	}
+}
+
+func TestNormalizeReasoningField_Streaming(t *testing.T) {
+	t.Parallel()
+	data := []byte(`{"choices":[{"delta":{"reasoning_text":"thinking delta"}}]}`)
+	got := normalizeGitHubCopilotReasoningField(data)
+	rc := gjson.GetBytes(got, "choices.0.delta.reasoning_content").String()
+	if rc != "thinking delta" {
+		t.Fatalf("reasoning_content = %q, want %q", rc, "thinking delta")
+	}
+}
+
+func TestNormalizeReasoningField_PreservesExistingReasoningContent(t *testing.T) {
+	t.Parallel()
+	data := []byte(`{"choices":[{"message":{"reasoning_text":"old","reasoning_content":"existing"}}]}`)
+	got := normalizeGitHubCopilotReasoningField(data)
+	rc := gjson.GetBytes(got, "choices.0.message.reasoning_content").String()
+	if rc != "existing" {
+		t.Fatalf("reasoning_content = %q, want %q (should not overwrite)", rc, "existing")
+	}
+}
+
+func TestNormalizeReasoningField_MultiChoice(t *testing.T) {
+	t.Parallel()
+	data := []byte(`{"choices":[{"message":{"reasoning_text":"thought-0"}},{"message":{"reasoning_text":"thought-1"}}]}`)
+	got := normalizeGitHubCopilotReasoningField(data)
+	rc0 := gjson.GetBytes(got, "choices.0.message.reasoning_content").String()
+	rc1 := gjson.GetBytes(got, "choices.1.message.reasoning_content").String()
+	if rc0 != "thought-0" {
+		t.Fatalf("choices[0].reasoning_content = %q, want %q", rc0, "thought-0")
+	}
+	if rc1 != "thought-1" {
+		t.Fatalf("choices[1].reasoning_content = %q, want %q", rc1, "thought-1")
+	}
+}
+
+func TestNormalizeReasoningField_NoChoices(t *testing.T) {
+	t.Parallel()
+	data := []byte(`{"id":"chatcmpl-123"}`)
+	got := normalizeGitHubCopilotReasoningField(data)
+	if string(got) != string(data) {
+		t.Fatalf("expected no change, got %s", string(got))
+	}
+}
+
 func TestApplyHeaders_OpenAIIntentValue(t *testing.T) {
 	t.Parallel()
 	e := &GitHubCopilotExecutor{}